The invention is applicable especially but non-restrictively to light three-wheeled vehicles of the type described in U.S. Pat. No. 3,698,502 filed by the same inventor.
In this patent a three-wheeled vehicle is described including a front wheel for steering and a back axle onto which is articulated the body of the vehicle so that the latter can tilt to one side or the other of the plane of symmetry of the axle. Thanks to this arrangement the vehicle is stable at standstill, the articulation being then blocked, which enables it to have a body for protecting the driver. But when running, the articulation is unblocked so that the vehicle can behave like a two-wheeled vehicle which enables the driver, in order to compensate for the effect of centrifugal force, to tilt the body towards the inside of the curve until the median plane passing through the center of gravity is directed along the direction of the apparent vertical, that is to say, of the resultant of the gravity and the centrifugal force.
However, one cannot count solely upon the sense of balance of the driver, above all if the vehicle has a body, and for safety it is useful to have available a means enabling the body of the vehicle to be kept along the convenient tilt. In French Pat. No. 1,562,248 and its Addition No. 2,031,813 a certain number of means have been described enabling the articulation of the body to be blocked when the median plane of it tends to deviate from the direction of the apparent vertical. In the patent already quoted, the different means of control for maintaining the tilt of the body are operated by a pendular mass consisting either of a pendulum articulated onto the body or a rolling mass, for example, a ball capable of moving over a pan in the form of a cylindrical surface having an axis parallel with that of the articulation.
In these vehicles the stability depends obviously upon the sense of balance of the driver. Now that depends upon persons and may otherwise be disturbed by the fact that the vehicle has a body and hence has a weight necessarily higher than that of conventional two-wheeled vehicles and that furthermore it is more sensitive to sidewind.